KiloVault LiFePO4 on MX60

Discussion about the MX60 Charge Controller

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Zachrey
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My RE system: 4 Scheuten 230 Watt photovoltaic panels. 920 Watts total
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Location: Greater World earthship subdivision, 13 mile NW of Taos New Mexico

KiloVault LiFePO4 on MX60

Post by Zachrey » Mon Jun 24, 2019 12:07 pm

Hi Everyone!

I have an MX60 controller that I just switched over to LiFePO4 and have a funny thing happening...

I set the Absorb voltage for 27.6V (with shortest possible absorb time of 6 minutes, 0.1hr) and the float voltage to 26.8V, which is quite close to the Mfrs spec.

I stuck a homebrew data logger on the puppy to make sure everything is working as expected and got the following results:

Normal ramp up in battery voltage and battery current from sunrise to about 10:30am. Once it reaches the absorb voltage, it says "CHARGED" then it goes to "SNOOZING" then it goes to "TRACKING" and then goes to "MPPT BULK" and then back to "CHARGED". This curious phenomena repeats 16 times and it FINALLY settles on "FLOAT"!

I subsequently changed the Absorb end amps parameter from 0Amps to 10 AMps in hopes that it would stop the weirdness, but will need to harvest the data from the logger to find out later today.

Sorry for the jumbled images. This editor is buggy.

Here is the Amps time series:


Here is the voltage time series
rust_go22_minutely_vmean0_normed_20190620.jpg
Voltage time series
Here is a zoom in on the Amps
rust_go22_secondly_amean0_20190620_zoom2.jpg
Amps zoom in
Here is the Voltage zoom in
rust_go22_minutely_vmean0_normed_20190620.jpg
Voltage time series
Attachments
rust_go22_secondly_vmean0_normed_20190620_zoom2.jpg
Voltage zoom in
Zachrey Helmberger
Greater World subdivision
zachreynm@gmail.com
skype: zachreybc

raysun
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Re: KiloVault LiFePO4 on MX60

Post by raysun » Mon Jun 24, 2019 8:08 pm

Have you tried charging the battery from another, non-solar, charger for comparison?

Tillerman39A
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Re: KiloVault LiFePO4 on MX60

Post by Tillerman39A » Wed Sep 02, 2020 5:27 pm

Hi, Did you resolve your situation with the MX60 charging LiFePo4 batteries and if so what changes did you have to make. I ask because I am using an MX60 and will soon be installing (4) 24V 200ah LiFePo4 batteries.

Thanks.

raysun
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Re: KiloVault LiFePO4 on MX60

Post by raysun » Thu Sep 03, 2020 9:17 am

One issue with Lithium batteries is when full charge is approached, the accepted current drops off precipitously. At very low charging current, the controller loses regulation.

I don't know if that's the case in the OP, but the data appear to have that signature.

Tillerman39A
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Re: KiloVault LiFePO4 on MX60

Post by Tillerman39A » Thu Sep 03, 2020 4:58 pm

OBP does not reccomend using the MX60 for Lithium Ion battery applications and I'm wondering if this is the reason? It is my understanding though, there are a still a few out there using the MX60, but probably not maximizing the LI batteries quicker charging capabilities as the MX60 is designed for a slower charging algorithm. I'm still curious to know if Zachrey was able to resolve his issues?

My plan now is to find another charger that is LI friendly, possibly the Flexmax FM60, which according to the OBP Application Note about charging LI Batteries is compatible. Although I've read the FM60's User Manual/Specs and see no explanaition as to why it is capable to do so as opposed to the MX60. There is no LI Battery parameter settings as I can tell, so the charging algorithms are still designed for FLA batteries.

I am wondering if OBP is assuming that the LI batteries being used DO NOT have BMS imbedded into each module, which in that case would be an issue. Many LiFePo4 batteries sold these days however do include BMS built in, my batteries included. I really would like to get clarification on this issue from OBP. I don't think I'm the only one out there thinking about this. LI batteries are getting more affordable these days and I'm sure people are slowly switching over.

Thanks to anyone who can give clarification on this issue.

raysun
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My RE system: Flexpower One: FX3048T, (2) FM80, MATE3s, FlexNetDC
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Hyundai 355 watt panels (6 - 3 strings of 2 in series)
Honda EU7000is gas fuel generator

Re: KiloVault LiFePO4 on MX60

Post by raysun » Fri Sep 04, 2020 12:34 am

Agreed, there is not much out there to explain the reasoning behind why some equipment is not Lithium compatible while other devices are.

Its true that the OB gear (and essentially nearly everyone's gear) is Lead Acid battery oriented. However, that does not preclude the programmable chargers from adapting to Lithium as long as their parameters can be set to match the charging profile of the battery.

Using the most "published" integration available: OB and SimiPhi as a model, it may be fruitful to study the two companies' documentation, integration guides, and application notes to get a sense of what should, can, and can't be done to deploy lithium batteries.

On the question of OB not considering the vendors' BMS, I don't get the sense that is the case. Rather, in the case of SimpliPhi, the battery vendor flatly states that should the charging or discharging operations cause the BMS to go into protection, it can destroy the battery, and voids the warranty. All the docs I've read from both Phi and OB speak to setting parameters that avoid such an event entirely.

Though I have no citation I can point to, IMO, the MX series don't have tight enough control to handle the more critical boundary conditions of lithium cells. The FM controllers do.

For a reason completely unrelated to this discussion, I'd suggest spending the extra bucks, and opt for the FM80 over the FM60.

I'm about to spend my entire weekly allowance for the rest of my life on a lithium battery and equipment upgrade. I've been studying the integration issues fairly closely, as well as the new equipment trends. Just today, I was up at our area's major supplier looking over the latest in charger, inverter and battery tech. There's definitely a trend in enhanced battery/device communication going on. However, looking at the cutting edge from several of the inverter/charger vendors, and the battery vendors shows emerging capabilities that show promise, but to me, are not fully baked. For myself, the last thing I want to deal with down the road is battery degradation as the result of faulty handshaking between a bunch of vendors' 1.0 firmware releases.

In the end, I'm opting for some older charger tech that can be tweaked to accomodate the new battery tech. The equipment vendor and the battey vendor both agree on what works, and if they are right, I'll be happy.

If the folks vending the PowerVault battery have undertaken a similar effort to publish integration specs, you should have little problem getting them to work with OB equipment.

Tillerman39A
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Re: KiloVault LiFePO4 on MX60

Post by Tillerman39A » Fri Sep 04, 2020 10:05 am

Thank you for your insight, it is much appreciated. It appears we are on similar paths with the integration of LI batteries with our OB equipment. Perhaps in the future we should start a unique forum index concerning the use of LI batteries and the specifics of how to adapt the OB products to integrate efficiently, but of course I will know more after I actually install and have the experience of day to day use of this system. I will remain in contact through this forum and pass on any insights as I learn them.

Also, could you please ellaborate on the differences, beyond the obvious operational specs, of using the FM80 verses the FM60.
My array puts out 1,440 watts (configured 2 strings of 3) for 88Vmp, 16A Imp, and 110 Voc.

Thanks

raysun
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Posts: 2786
Joined: Tue Jul 26, 2016 5:57 am
My RE system: Flexpower One: FX3048T, (2) FM80, MATE3s, FlexNetDC
Outback 200NC batteries (8 @ 48v)
Outback IBR3 battery enclosure
Suniva 330 watt panels (12 - 6 strings of 2 in series)
Hyundai 355 watt panels (6 - 3 strings of 2 in series)
Honda EU7000is gas fuel generator

Re: KiloVault LiFePO4 on MX60

Post by raysun » Fri Sep 04, 2020 10:11 am

The biggest physical difference between the FM60 and FM80 is serviceability of the part most likely to fail - the internal fan.

On the FM60 the fan is mounted on the back of the chassis and requires a complete disassembly of the unit to replace. On the FM80, the fan is mounted behind the front cover and is much easier to access and replace.

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